Hey Max, I don't know of any specific apps, but could you use the default calendar app built into the phone, or any spreadsheet app?

As to good apps for events generally... There's a lot out there. There's light meters, viewfinders, gel swatches, storyboards... But, to be honest, the most useful apps for me are:
-- a weather app
-- a sunrise/sunset times app
-- a flashlight.

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